It is gratifying to know that the engineering profession has not been forgotten when honors have been conferred on distinguished men; and among others may be named Sir William Fairbairn, Sir John Rennie, Sir Peter Fairbairn, Sir Charles Fox, Sir William Armstrong, Sir Joseph Whitworth, Sir John Hawkshaw, Sir John Coode, Sir William Thomson, Sir Joseph Bazalgette, Sir Charles Hartley, Sir Charles Bright, Sir James Ramsden, Sir John Anderson, Sir George Elliot, Sir Daniel Gooch, Sir Henry Tyler, Sir Samuel Canning, Sir Edward Reed, and Sir Frederick Bramwell. With many noble examples before us, and with signs of an improvement in many branches of commerce, he trusted that the latter part of the present century will, with somewhat greater exertion of thought and enterprise on our parts, be marked, not only by numerous small improvements, but by many substantial inventions for the good of mankind.

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THE HOBOKEN DRAINAGE PROBLEM.

Our thriving neighbor, Hoboken, just across the Hudson River, has a large and vitally important problem to solve. Of the 720 acres within the city limits, 270 acres lie at a considerable height above the river and constitute what are known as the knoll or uplands of Hoboken. Between this low ridge and Palisade Ridge lie 450 acres of marsh lands or meadows, 140 acres of which have already been built upon. The marsh is about half a mile wide, and something like a mile and a half long, extending southward into Jersey City. The surface is a network of matted vegetation and roots perhaps five feet deep, and under that lies a mass of blue clay or river silt 100 feet or more in depth. The original tidal flow over these marsh lands has been obstructed by viaducts for railroads and streets, leaving only two natural outlets, a sluice way at Fifteenth street on the north, and on the south a basin constructed by the D. L. & W. R. R., 100 feet wide, and 2,300 feet long. The average level of the marsh land is three feet above mean low water and a foot and a half below mean high water. In the part built upon the streets are but two feet above mean high water.

During long easterly and northerly storms, especially at times of high spring tides, the level of the water in the Hudson is often such as to cover the meadows even at low tide; and on several occasions the water at high tide has been 41/2 feet above the level of the meadows, and a foot or more above the established grade of the streets.

The problem is to drain these marsh lands so as to make them properly habitable and to protect them from invasion by high tides and storm waters.

The first drainage map of the district was made about fifteen years ago; since then over $100,000 have been expended on tidal sewers and other devices, and several acts have been passed by the New Jersey Legislature in furtherance of the work. An extended review of the plans proposed and the experiments made thus far is given in a report presented to the Board of Health and Vital Statistics, last May, by Engineers Spielmann and Brush. Ten years ago Mr. Arthur Spielmann, on being directed by the City Council to prepare plans and estimates for a contemplated sewer in Ferry street to the western boundary of the city, reported adversely to the project, believing that such a sewer would fail to answer the purpose of its construction.

There were but two ways, he thought, of securing the end desired: First, by raising the grade sufficient to give a good drainage; second, by making reservoirs and forcing the drainage matter out into the river by steam pumps. The first method he found impracticable on account of the cost of filling in so large an area and of raising the large number of houses already on the low ground. The second plan was recommended as being much cheaper and entirely practicable. Substantially the same position is taken in the report of last May, wherein it is alleged that the superior economy of a pumping system has been sufficiently attested by several eminent hydraulic engineers who have since investigated the problems involved. On a small scale the efficacy of the pumping system has been practically tested, first, in Meadow street, between Ferry and First streets, and more recently in the southern part of the city, where a number of property owners have kept twenty-five acres free from water (except during storms) by means of a private pump.

The comparative economy of the pumping system is shown by estimates in detail of the cost of constructing and operating such a system in contrast with, the cost of raising the grade and introducing tidal sewers. Under both systems the cost of the ordinary sewers will be about the same. A proper system of tidal sewers, it is claimed, will necessitate the raising of the grade of the streets on the low lands to a height at least ten feet above mean high water. The extra cost of raising the streets is estimated at $3,000,000. The cost of the pumping system, with machinery and power sufficient to remove all storm water and sewage, is put at $150,000, while the running expenses, including interest on the first outlay, are put at $30,000 a year. The interest on the preliminary expenditure of the first plan considered is $180,000 a year, or six times as much as the pumping system would involve.

According to the estimates made by Engineer Kirkwood, in his report of 1874, a total pumping capacity of 134,500,000 gallons a day will ultimately have to be provided to meet the requirements during the heaviest storms, besides some six or seven million gallons a day of sewage proper, exclusive of storm waters. Not more than half that amount of pumping will be required at first, the increase to be made gradually as the marsh land is built upon.

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ARTISTS' HOMES—No. 14—"BENT'S BROOK."

Our plate illustrates the residence of Mr. J. E. Boehm, A.R.A., the sculptor. Bent's Brook is situated at Holmwood, not far south of Dorking, on the Mid-Sussex line, and commands some fine views of well-timbered country. The site itself is comparatively low, and the soil being clay it was advisable to keep the building well out of the ground, and in this way a rather unusually high elevation for such a house was obtained. The plan is very compactly arranged, with an ingenious approach to the well-centered hall and staircase, over which, by a mezzanine contrivance, a good store place is secured. The drawing-room has a belvedere bay, reached from the garden by an external stair, under which is a covered garden seat. A balcony overlooking the garden leads also from the drawing-room, and a billiard room is arranged on the basement level with a separate entrance from the porch. A tradesmen's entrance is provided elsewhere. The kitchen and offices are on the lower floor level, and a kitchen yard is conveniently placed at the rear. Red brick, with cut-brick dressings, is the material used throughout for the walls, the upper parts of which are hung with ornamental tiles. The gables are enriched with wide, massive barge boards, and the roof is surmounted with a white wooden cupola over the principal staircase. The terracotta panels along the entrance front, over the principal floor windows, were designed by Mr. Boehm himself. The work was executed by Mr. H. Batchelor, builder, of Betchworth, and the architect of the house was Mr. R. W. Edis, F.S.A., who superintended its erection.—Building News.



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ON SOME RECENT IMPROVEMENTS IN LEAD PROCESSES.

[Footnote: Lately read before the Institute of Mechanical Engineers.]

By NORMAN C. COOKSON, of Newcastle.

The author began by stating that probably in few trades have a smaller number of changes been made during recent years, in the processes employed, than in that of lead smelting and manufacturing. He then briefly noted what these changes are, and went on to describe the "steam desilverizing process," as used in the works of the writer's firm, and in other works licensed by them, which process is the invention of Messrs. Luce Fils et Rozan, of Marseilles. It is one which should commend itself especially to engineers, as in it mechanical means are employed, instead of the large amount of hand-labor used in the Pattinson process. It consists in using two pots only, of which the lower is placed at such a height that the bottom of it is about 12 in. to 15 in. above the floor level, while the upper is placed at a sufficiently high level to enable the lead to be run out of it into the lower pot. The capacity of the lower pot, in those most recently erected, is thirty-six tons—double that of the upper one. Round each pot is placed a platform, on which the workmen—of which there are two only to each apparatus—stand when skimming, slicing, and charging the pots. The upper pot is open at the top, but the lower one has a cover, with hinged doors; and from the top of the cover a funnel is carried to a set of condensers. At a convenient distance from the two pots is placed a steam or hydraulic crane, so arranged that it can plumb each pot, and also the large moulds which are placed at either side of the lower pot. The mode of working is as follows:

The silver lead is charged into the upper pot by means of the crane. When melted, the dross is removed, and the lead run into the lower, or working pot, among the crystals remaining from a previous operation.

When the whole charge is thoroughly melted, it is again drossed; and in order to keep the lead in a thoroughly uniform condition, and prevent it setting solid on the top and the outside, a jet of steam is introduced.

To enable this steam to rise regularly in the working pot, a disk-plate is placed above the nozzle, which acts as a baffle-plate; and uniform distribution of the steam is the result. To quicken the formation of crystals, and thus hasten the operation, small jets of water are allowed to play on the surface of the lead.

This, it might be thought, would make the lead set hard on the surface; but the violent action of the steam acts in the most effectual manner in causing the regular formation of crystals. Owing to the ebullition caused by this action of the steam, small quantities of lead are forced up, and set on the upper edges and cover of the pot. From time to time the valve controlling the thin stream of water playing on the top of the charge is closed, and the workman, opening the doors of the cover in rotation, breaks off this solidified lead, which falls among the rest of the charge, and instantly becomes uniformly mixed with it.

Very little practice enables an ordinary workman to judge when two-thirds of the contents of the big pot are in crystals, and one-third liquid; and when he sees this to be the case, instead of ladling out the crystals ladleful by ladleful, as in the old Pattinson process, he taps out the liquid lead by means of two pipes, controlled by valves, the crystals being retained in the pot by means of perforated plates.

The liquid lead is run into large cone-shaped moulds on either side of the pot; and a wrought iron ring being cast into the blocks thus formed, they are readily lifted, when set, by the crane. To give some idea of the rapidity of the process, it may be mentioned that from the time the lead is melted and fit to work in the big pot, to the time that it is crystallized and ready for tapping, is, in the case of a 36 ton pot, from thirty-five to forty-five minutes; and the time required for tapping the liquid lead into the large moulds is about eight minutes.

Before the lead begins to crystallize, the upper pot is charged with lead of half the richness of that in the lower pot. Thus, when the liquid lead has been tapped out of the lower pot, it is replaced by a similar amount of lead of the same richness as the remaining crystals, by simply tapping the upper or melting pot, and allowing the contents to run among the crystals.

The same operation is repeated from time to time, until the crystals are so poor in silver that they are fit to be melted, and run into pigs for market.

The large blocks of partially worked lead are placed by the crane in a semicircle round it, and pass successively through the subsequent operations. The advantages of the steam process, as compared to the old six-ton Pattinson pots formerly used by the writer's firm, are: (1) a saving of two-thirds amount of fuel used; (2) the saving of cost of calcination of the lead to the extent of at least four-fifths of all that is used; (3) above all, a saving in labor to the extent of two-thirds. The process has its disadvantages, and these are a larger original outlay for plant, and a constant expense in renewals and repairs. This is principally caused by the breakage of pots; but with increased experience this item has been very much reduced during the last two or three years.

The "zinc process" of desilverizing, which is largely used by Messrs. Locke, Blackett & Co., and was patented in the form adopted by them about fourteen years since. The action of this process is dependent on the affinity of zinc for silver. The following is a brief description of it:

A charge of silver lead, usually about fifteen tons, is heated to a point considerably above that which is used in either the Pattinson or the steam process. The quantity of zinc added is regulated by the amount of silver contained in the lead; but for lead containing 50 oz. to the ton, the quantity of zinc used is in most cases about 11/2 per cent, of the charge of lead. The lead being melted as described, a portion of this zinc, usually about half of the total quantity required for the charge, is added to the melted lead, and thoroughly mixed with it by continued stirring. The lead is now allowed to cool, when the zinc is seen gradually to rise to the top, having incorporated with it a large proportion of the silver. The setting point of zinc being above that of lead, a zinc crust is gradually formed, and this is broken up and carefully lifted off into a small pot conveniently placed, care being taken to let as much lead drain off as possible. The fire is again applied strongly to the pot, and when the lead is sufficiently heated, a further quantity of zinc, about one-third of the whole quantity used, is added, when the same process of cooling and removing the zinc crust is repeated. This operation is gone through a third time with the remaining portion—1/4 per cent.—of zinc; and if each of these operations has been carefully carried out, the lead will be found to be completely desilverized, and will only show a very small trace of zinc. In some works this trace of zinc is allowed to remain in the market lead, but at Messrs. Locke, Blackett & Co.'s works it is invariably removed by subjecting the lead to a high heat in a calcining furnace. The zinc crusts, rich in silver, are freed as far as possible from the lead by allowing this to sweat out in the small pot, after which the crusts are placed in a covered crucible, where the zinc is distilled off, and a portion of it recovered. The lead remaining, which is extremely rich in silver, is then taken to the refinery, and treated in the usual manner. The writer is given to understand that the quantity of zinc recovered is as high as from 50 to 60 per cent. of the total quantity used.

Although it was said that the rolling or milling of lead remains unchanged in its main features since the first mill was established, yet the writer's firm have introduced many important improvements. When lead is required for sheet making, instead of running out the market lead into the usual pigs of about one hundredweight each, it is run into large blocks of 31/2 tons. These 31/2 ton blocks are taken on a bogie to the mill-house, where the mill melting pot is charged with them by means of a double-powered hydraulic crane, lifting, however, with the single power only.

Three such blocks fill the pot, and when melted are tapped on to a large casting plate, 8 ft. 4 in. by 7 ft. 6 in., and about 7 in. thick. This block, weighing 101/2 tons, is lifted on to the mill table by the same crane as fills the pot, but using the double power; and is moved along to the rolls in the usual manner by means of a rope working on a surging head. The mill itself, as regards the roll, is much the same as those of other firms; but instead of an engine with a heavy fly-wheel, always working in one direction, and connected to the rolls by double clutch and gearing, the work is done by a pair of horizontal reversing engines, in connection with which there is a very simple, and at the same time extremely effectual, system of hydraulic reversing. On the usual method there is no necessity for full or delicate control of lead mill engines; but with this system it is essential, and the hydraulic reversing gear contributes largely to such control. This may be explained as follows:

In all other mills with which the writer is acquainted, when the lead sheet, or the original block, has passed through the rolls, and before it can be sent back in the opposite direction, a man on either side of the mill must work it into the grip of the rolls with crowbars.

In the writer's system this labor is avoided, and the sheet or block is fed in automatically by means of subsidiary rolls, which are driven by power. When it is required to cut the block or sheet by the guillotine, or cross-cutting knife, instead of the block being moved to the desired point by hand-labor, the subsidiary driven rolls work it up to the knife; and such perfect control does the engine with its hydraulic reversing gear possess, that should the sheet overshoot the knife 1/8 in., or even less, the engine would bring it back to this extent exactly.

Another point, which the writer looks upon as one of the greatest improvements in this mill, is its being furnished with circular knives, which can be set to any desired width, and put in or out of gear at will; and which are used for dressing up the finished sheet in the longitudinal direction. This is a simple mechanical arrangement, but one which is found to be of immense benefit, and which, in the writer's opinion, is far superior to the usual practice of marking off the sheet with a chalk line, and then dressing off with hand knives. The last length of the mill table forms a weighbridge, and a hydraulic crane lifts the sheet from it either on to the warehouse floor or the tramway communicating with the shipping quay.

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APPARATUS USED IN BERLIN FOR THE PREPARATION OF GELATINE PLATES.

I.—MIXING APPARATUS FOR GELATINE EMULSION.

The mixing vessel—a porcelain kettle capable of containing twenty liters, made at the Royal Porcelain Factory at Berlin, whose products are unequaled for chemical purposes—is also the boiling vessel, and, therefore, fits tightly, by means of the tin ring with the wooden handles, on to a large water bath. The light-tight metal lid, which can be permanently affixed to the kettle, then supports a stirring arrangement of fine silver, which dips into the emulsion and has blades formed like a ship's screw.

The arrangements for injecting the silver vary. The simplest consists of a large glass vessel containing the silver solution, which is closed by a glass stopper, and terminates below in a funnel running to a fine point. This funnel-shaped bottle fits into an opening specially made for it in the lid of the kettle, and while revolving sends a fine stream into the gelatine. When it is wished to interrupt it, it is only necessary to raise the glass stopper in order to see the stream dry up after a short time.

Another arrangement consists of a contrivance constructed on the principle of the common India-rubber inhaling apparatus, and sends the silver solution into the gelatine in the form of the minutest air-bubbles. After the emulsion is boiled in such a kettle it is allowed to stand until cool, when the ammonia is added. With such a great quantity of emulsion and so large a water bath sufficient heat is retained as to allow the action of the ammonia to take place. As soon as the time set apart for that reaction has elapsed the water bath is emptied and filled with pieces of ice and iced water, and the kettle replaced in it.

If the stirring apparatus be now set in motion, even this large quantity of emulsion will stiffen in at least an hour and a half. It may be further remarked that, the outside of the kettle being black, the lid being light-tight, and all the apertures in it being firmly closed, nearly the whole process can be conducted by daylight, from the mixing to the stiffening, so that it is very convenient to be able to keep the emulsion in the same vessel during all these operations.

II.—DIGESTIVE APPARATUS.

It is very desirable that those who do not prepare their emulsion by boiling, but by prolonged digestion, should possess a regulator which will keep the temperature at a given point. Such an apparatus would also be very useful for warming the emulsion for the preparation of plates, as then one would have no further occasion to pay attention to the thermometer and gas stove. In the accompanying diagram a simple contrivance is shown. The gas which feeds the stove passes through a narrow glass tube, a b, into the wider tube, c d e, which is made air-tight at e. This latter tube has an exit tube at f, by which the gas is supplied to the gas stove. At e it is hermetically closed, and at its deepest part it contains mercury, upon which a little sulphuric ether floats in the hermetically-closed limb, e.g. Lastly, there is a minute opening in the narrowest tube at i. The whole apparatus, or, at least, the under part of it, is dipped into the water bath warmed by the gas boiler. It acts thus: As the temperature rises the ethereal vapor in the shorter limb expands and drives the mercury up the longer tube until it closes the opening of the narrow tube, a b, and thereby impedes the power of the stream of gas. Still, the Bunsen burner does not go out, being always fed by the small opening, i, with sufficient gas to support a small flame until the water bath has so far cooled as to leave the opening at b free, when the burner again burns with a strong flame. By removing the cork, c, from the tube the temperature of the water bath is raised, while by pushing it in it is lowered. The apparatus never goes wrong, and is very cheap. It was first made by Herr C. Braun, of Berlin.



III.—TRITURATING APPARATUS.

The apparatus hereafter described is in general use, and was invented by Herr Paul Grundner, of Berlin. It is particularly adapted for finely dividing large quantities of emulsion. It consists essentially of a wooden lid, a b, fitting upon a large stone pot, to the under side of which two strong trapezoid pieces of wood, e d and e f, are fixed, in the under part of which semicircular incisions are cut and held together by two leather straps, supporting a strong, easily-removable iron transverse bar, g h. Through the center of the lid, and turned by the crank, m, passes the axle i, which ends under the lid in the long ring, n.

The stiffened emulsion is then placed in the bag, o p q r, made of fine but strong canvas, with meshes about 0.5 mm. (such as is used for working upon with Berlin wool). The iron rod, g h, is then slipped through the four loops at the bottom of the bag, the open end is slung upon the ring, n, and bound tightly to it by the ribbons, r1. The loops upon the iron bar are then pushed as close together in the middle as possible, and the stone vessel is filled with water until o p q r is completely covered. The crank is then turned, by which the bag is wrung, and the emulsion squeezed through the meshes immediately into the water. When this process is continued until the purse between n and g h feels like a metal rod, the best part of the emulsion has been squeezed through, and if one now take out the bag and dissolve its contents, it will be found that the loss of emulsion is almost nil.



It may be remarked that the whole apparatus, with the exception of the crank, must be coated with asphalt varnish; also that the corners, r and q, must be separated off from the purse, as shown by the dotted line, s s s s, otherwise the emulsion would lodge there without being squeezed through. Instead of g h a strong glass rod may be used for small apparatus; but for large apparatus it is indispensable, as the power that requires to be exerted would be far too great for glass.

IV.—WASHING APPARATUS.

The fundamental idea of the apparatus shown in Fig. 3 first occurred to Herr Jos. Junk, of Berlin. In the present form all the subsequent improvements made by Herren Carl Such, Paul Grundner, and others are incorporated. It may be described as follows:

A tin vessel, the bottom of which sinks at e into the shape of a funnel, rests upon strong iron feet, f f, and is covered with a lid, having a double edge closing it light-tight. Through the center of the lid passes the tube, g h, by which the water enters. In the interior of the vessel upon iron hooks stands a wooden vessel saturated with paraffine, open at the ends, and over one end of which the finest hair cloth is stretched at o p. The water which enters the vessel runs off through the siphon. The proceedings are as follows: Turn the granulated gelatine and the water in which it is contained into the horsehair sieve, m n o p. Place the lid upon the apparatus and turn on the water. The whole apparatus fills with water until the siphon begins to act. If the diameter of the siphon be properly measured—one inch should be sufficient for the largest apparatus—and the cock by which the water is turned on properly adjusted, more water will run out by the siphon than runs in through the supply pipe, and the apparatus becomes completely empty.

The siphon has then performed its function, the apparatus fills again, and the play begins anew. The tube, g h, which reaches right down nearly to the bottom of the sieve, takes the water so deep into the vessel that, as long as the water in the apparatus stands high enough above o p, the gelatine nodules are in continuous motion. In order to prevent the finest particles of the emulsion from stopping up the pores of the sieve too much, and thereby incurring the danger of the water in the sieve overflowing its upper edge, thus occasioning loss of emulsion, the tube, g h, is now sometimes omitted and replaced by a supply pipe, represented in the diagram by the dotted lines, x y. In this way every possibility of loss is excluded, and yet a very careful washing provided. Then when, after being emptied by the siphon, the apparatus fills again, every particle of the emulsion which might have formerly been pressed down into the interstices of the sieve would now be driven up again by the upward pressure of the water entering from below, and thus the sieve would always be kept clear and open.



The great advantages of this apparatus are as follows: 1. From the moment the lid is closed one can work by daylight. 2. The method of washing in moving water is combined with that of complete change of water. 3. The emulsion never comes in contact with metal. 4. Whoever wishes to prepare dry gelatine only requires, when the washing is over and the vessel perfectly emptied, to leave the emulsion to drip for a time, and then to lift out the sieve and its contents and place it in a suitable vessel with absolute alcohol. The latter should be changed once, and when sufficient water has been extracted the sieve should be withdrawn from the vessel and the emulsion allowed to dry spontaneously. In this way all trouble occasioned by changing from vessel to vessel is avoided, and there is no loss of material.

This apparatus is principally valuable in dealing with large quantities, since it saves a great deal of labor, and affords perfect certainty of the emulsion being well washed. It may not be unnecessary to maintain that the difficulties of perfect washing—particularly if one do not wash with running water—increase at least in quadruple proportion to the quantity of emulsion manipulated.—Franz Stoke, Ph.D., in Br. Jour, of Photography.

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HOW TO MAKE EMULSION IN HOT WEATHER.

By A. L. HENDERSON.

Numerous complaints have reached me within the last few weeks of the difficulty experienced in preparing emulsion and coating plates; one is very likely to blame everything but the right, but doubtless the weather is the culprit.

I have always held that to boil gelatine is to spoil it, and, even when emulsification is made with a few grains to the ounce and cooled down before adding the bulk, the damage is done to the smaller quantity, so that when mixed it contaminates the whole mass; moreover, it is impossible to set and wash the gelatine without the aid of ice.

I have lately made several batches (with the thermometer at 92 deg. in the shade, and the washing water at 78 deg.) as follows:

Hard gelatine...............,...... 1/2 ounce. Water.............................. 2 ounces. Alcohol............................ 2 " Bromide ammonia....................150 grains. Liquor ammonia, 880................ 60 drops.

When all is thoroughly dissolved and of about 120 deg. temperature, add, stirring all the time,

Nitrate silver..................... 60 grains, Water.............................. 3/4 ounce. Alcohol............................ 3/4 "

Then again add,

Nitrate silver.....................140 grains. Water.............................. 1 ounce. Alcohol............................ 1 "

Both solutions being warmed to about 120 deg..

My object is adding the silver in two quantities will be obvious to many—viz., when the first portion of silver is mixed, nitrate of ammonia is liberated (which is a powerful restrainer), and the bulk of the solution being increased, the remainder of the silver may be added in a much more concentrated state.

The alcohol, both in the gelatine and silver solutions, plays a most important part: (1) It prevents decomposition of the gelatine. (2) It allows the gelatine to be precipitated with a much smaller quantity of alcohol (say about 10 ounces).

After letting the emulsion stand for a few minutes to ripen, I pour in slowly about eight ounces of alcohol, stirring all the time, and keeping the emulsion warm; the emulsion will adhere to the stirring-rod and the bottom of the vessel in a soft mass, and all that is now required is to pour away the alcohol, allow the emulsion to cool, tear it into small pieces, wash in several changes of cold water, make up the quantity to ten ounces, and strain; it is then ready for coating.

By this formula I have no difficulties whatever; my plates set in about five minutes, and their quality is such that, "unless a better method is devised," I intend to adopt it in all weathers.

One word more as to the alcohol. It will prevent the decomposition of gelatine when boiling goes on, or when in the presence of foreign salts; no flocculent deposit is noticed in the alcohol after the emulsion has been precipitated.—Photographic News.

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THE DISTILLATION AND RECTIFICATION OF ALCOHOLS BY THE RATIONAL USE OF LOW TEMPERATURES.

By RAOUL PICTET.

The industrial problem of the rectification of alcohols is based entirely upon the properties of volatile liquids, upon the laws of the maximum tensions of the vapors of these liquids, and upon the influence of temperature upon those different elements which find themselves in presence of each other in an alembic.

If we desire to follow, in their least details, all the phenomena which succeed one another in a rectifying column, and which are connected with one another by a continuous chain of reciprocal influences, the problem becomes exceedingly complex.



In order that the new applications of the mechanical theory of heat may be readily understood, we shall divide this problem into a series of propositions, which we shall examine separately, and which collectively constitutes in its general features the methodical rectification of liquids.

I. Knowing the maximum tensions of pure water and pure alcohol, can we calculate directly the tensions of the vapors of any mixture whatever of alcohol and water?

Yes, we can calculate this tension by a general formula, provided we take into account the affinity of water for alcohol, which increases the value of the total latent heat of evaporation of the liquid. The results of the calculation are fully confirmed by experience. We thus establish the following laws:

a. For any temperature whatever, the maximum tension of the vapors of a mixture of water and alcohol is always comprised between that of pure water and that of pure alcohol.

b. The tension of the vapors of a mixture of water and alcohol approaches the tension of alcohol so much the nearer in proportion as the proof is higher; and, reciprocally, if water is in excess, the tension of the vapors approaches the tension of the vapors of water.

c. The curves of the maximum tensions of vapors formed by all mixtures of alcohol and water are represented by the same general formula, one factor only of which is a function of the richness of the alcoholic solution.

It results, then, from these laws that we may determine with the greatest exactness the richness of a solution containing alcohol and water, if we know the tension of the vapors that it gives off at a certain temperature. Such indications are confirmed by the centigrade alcoholmeter.

We see likewise that, for these solutions of alcohol and water, the laws of Dalton are completely at fault, since the total pressure of the vapors is never equal to the sum of the tensions of the two liquids, water and alcohol.

II. Being given a solution of water and alcohol, mixed in equal volumes, what will be the quality of the vapors emitted from it?

In other terms, do the vapors which escape from a definite mixture of water and alcohol also contain volumes of vapor of water and alcohol in the same proportion as the liquids?

We have discovered the following laws:

d. The quality of the vapors emitted by a mixture of water and alcohol varies according to the alcoholic richness of the solution, but is not in simple proportion thereto.

e. The quality of the vapors emitted by a definite mixture of water and alcohol varies according to the temperature.

f. In a same solution of water and alcohol, it is at low temperatures that the vapors emitted by the mixture contain the largest proportion of alcohol.

g. The more the temperature rises the more the tensions of the two liquids tend to become equalized.

We have been able to verify these different laws experimentally, and to find an interesting confirmation of our general formula of maximum tensions, in the following way:

Let us take a test tube containing a 50 per cent. solution of alcohol and water, plunge it into water of 20 deg.C., and put its interior in hermetic communication with the receiver of a mercurial air-pump.

We vaporize at 20 deg. a certain quantity of the liquid, and the vapors fill the known capacity of the pump. The pressure of the gases in the interior is ascertained by a pressure gauge, and this pressure should be constant if care is taken to act upon a sufficient mass of liquid and with moderate speed. When the receiver of the air-pump is full of vapors, communication between it and the test-tube is shut off, and communication is effected with a second test-tube, like the first, plunged into the same water at 20 deg.. Care must be taken beforehand to create a perfect vacuum in this test-tube.

On causing the mercury to rise into the space that it previously occupied, the vapors are made to condense in the second test-tube at the same temperature as that at which they were formed.

We immediately ascertain that the pressure-gauge shows an elevation of pressure; moreover, the proof of the condensed alcohol has very perceptibly risen.

If, instead of causing these vapors to condense in the second test-tube, we leave the first communication open, the vapors recondense in the first test-tube without any elevation of pressure; and we do not see the least trace of liquid forming in the second test tube.

This difference of pressure in the two foregoing experiments must be attributed, then, to the specific action of the water on the vapors of alcohol. Now we can calculate the difference of the work of the pump, and put at 1 kilogramme of condensed liquid the difference of mechanical work represented in kilogrammeters. What is remarkable is that this difference is absolutely the equivalent of the heat disengaged when the condensed liquid and the old liquid are remixed; there is a complete identity. Thus the affinity of the water for the alcohol modifies the tension of the vapors which form or condense upon the free surface of the mixture. The two phenomena are closely connected by the law of equivalence.

It results from all the laws that we have cited that by properly regulating the tensions of the vapors of a mixture of alcohol and water, and the temperature of the liquid, we shall be able to obtain a liquid of a desired richness by the condensation of these vapors.

III. It was likewise indispensable to make sure of one important fact: When the temperature of a liquid like alcohol is considerably lowered, can the distillation of a given weight of this substance be effected with sufficient rapidity for industrial requirements? Repeated experiments with a host of volatile liquids have demonstrated the following laws:

If we introduce a volatile liquid into two spherical receivers connected by a wide tube, and if these be kept at different temperatures after driving out all the air from the apparatus, the liquid distills from the warmer into the cooler receiver, and we ascertain that:

h. The weight of the liquid which distills in the unit of time increases with the deviation of temperature between the two receivers.

i. The weight of the liquid which distills in the unit of time is constant for a same deviation of temperature between the receivers, whatever be, moreover, the absolute temperature of the receivers.

k. The weight of the liquid distilled in the unit of time is proportional to the active surfaces of the receivers; that is to say, to the surfaces which are the seat of passage of heat through their thickness.

l. The least trace of a foreign gas in the vapors left in the apparatus throws the preceding laws into confusion, and checks distillation to a considerable degree, especially at low temperatures.

Thus, water distilling between 100 deg. and 60 deg. will pass over as quickly as that which is distilling between 40 deg. and 0 deg.. Absolute temperature is without influence, provided every trace of air or foreign gas be got rid of.

The distillatory apparatus should be provided with an excellent air-pump, capable of preventing all those entrances of air which are inevitable in practice.

The following is the industrial application that we have endeavored to make of these theoretical views: The rectification of alcohols is one of the most complex of operations; it looks toward several results simultaneously. Alcohol derived from the fermentation of grain, sugar, and of all starchy matters in general, contains an innumerable host of different products, which may be grouped under four principal heads:

1. Empyreumatic essential oils, characteristic of the source of the alcohol, and having a powerful odor which infects the total mass of the crude spirits. 2. A considerable quantity of water. 3. A certain quantity of pure alcohol. 4. A variable proportion of volatile substances, composed in great part of ethers, different alcohols, and bodies as yet not well defined. These latter affect the quality of the alcohol by an odor which is entirely different from that of the essential oils.

The object of rectification is to bring out No. 3 all alone; that is to say, to extract the alcohol in a pure state by ridding it of oils, water, ether, and foreign alcohols.

The alcohol industry never realizes this operation in an absolutely complete manner. All the rectifying apparatus in operation at the present day are based on the use of high temperatures varying between 78.5 deg. and 100 deg.. The successive condensation and vaporization of the vapors issuing from the spirits effect in the rectifying columns a partial separation of these liquids, and there are received successively as products of rectification:

1. Bad tasting alcohols, containing the majority of the ethers and impure alcohols.

2. Fine alcohol.

3. Alcohols contaminated by notable proportions of empyreumatic oils.

Industry knows only one means of obtaining an excellent product, and that is to diminish the quantity of fine alcohol which comes from a same lot of spirits, and to make a large number of successive distillations. Hence the large expenses attending rectification, which produce fine alcohols necessarily at an elevated price. We may remark, in passing, that the toxic action of commercial alcohols is in great part caused by the presence of essential oils, amylic alcohol, and ethers, absolutely pure alcohol, as compared with these, being relatively innocent.

Why is it that our present apparatus cannot produce good results in rectifying alcohol? Because they are limited by the temperature at which they must operate. Between 78 deg. and 100 deg. the tension of the vapors of all the liquids mixed in the spirits is considerable for each of them; they all pass over, then, in certain proportions during the operation of rectification.

We have been led, by examining the theoretical question, to ascertain that the proportion of alcohol which evaporates from a mixture is maximum at low temperatures; consequently, we should seek to establish some arrangement which can realize the following conditions: (1) Render variable, at will, the temperature of the boiling liquid; and (2), render variable the pressure of the vapors which act on the liquid.

Thus, to effect the rectification of alcohol it suffices to cause its ebullition at very low temperatures, and to keep up the ebullition without changing such temperatures when once obtained.

It is exactly these two conditions that we have fulfilled in the apparatus that we have just installed in our factory in Rue Immeubles Industriels, at Paris.

By their arrangement, which is shown in the opposite figure, they form a mechanical system permitting of the rectification of alcohols at temperatures as low as -40 deg. or even -50 deg.. They verify experimentally, by their operation, the theoretical deductions which precede. The boilers, A, which, in an industrial application, may be more numerous, receive their supply of spirits from the country distilleries in the vicinity of the factory. There may even be introduced directly into them vinasses, or washes, that is to say, liquids, such as are obtained by alcoholic fermentation.

Above the boiler rises a rectifying column composed of superposed plates inclined one over the other, and surmounted by a tubular condenser, which serves to effect the retrogression of the first condensation by means of a current of water supplied by the reservoir placed above.

On leaving this condenser, the vapors which have escaped condensation pass into the refrigerator, C, where they are totally condensed by a current of water which goes to the reservoir above.

The first products obtained contain ethers and impure alcohols, which are collected in the reservoir, E.

When the first products have been thus introduced into the reservoir, and it is ascertained by tasting that good alcohol is passing over, the liquid produced is directed into the second boiler, F. The sliding valve, operated by a screw having a very fine pitch, establishes a communication between the refrigerator, C, and the second boiler, F. The office of this valve we shall learn further on. This first rectification is performed in a vacuum, for a system of metallic pipes connects the entire apparatus with an air-pump, O. The temperature at which the liquids shall enter into ebullition in the boilers, A A, may, then, be regulated in advance.

The operations will be carried on with a more or less complete vacuum, according to the nature of the products to be rectified. The distiller will have to be guided in this by practice alone.

The good tasted products are received in boiler No. 2, F, and there the liquids are submitted to the action of an almost absolute vacuum. As we have before said, their temperature falls immediately and spontaneously. The vapors which issue from this liquid contain almost solely pure alcohol. The other substances, which passed over in the first distillation, no longer emit vapors at temperatures ranging between -10 deg. and +5 deg.. Their temperature is shown by a thermometer running into the boiler, F.

These vapors, purified by ebullition at a low temperature, rise into a second rectifying column, G, which terminates in the refrigerator, H, filled with liquid sulphurous anhydride. This refrigerator is like those which we employ in our sulphurous anhydride frigorific apparatus. Under the action of a special pump, M, this liquid produces and maintains a constant temperature of -25 deg. to -30 deg. in the refrigerator. The vapors of alcohol condense therein at this low temperature, and the cold liquid alcohol flows into the lower part of the refrigerator.

By the action of a return cock, a portion of this liquid falls upon the plates of the column, G, and descends, while the vapors are rising therein. The other portion of the liquid obtained flows into the reservoir, K, at the beginning of the operation, and into the reservoir, L, during all the remainder of the rectification. The ice-making machine keeps up of itself alone the two operations.

In fact, the exhaust of the steam engine which actuates the sulphurous anhydride pump is directed into a worm which circulates through the first boiler, A, and the refrigerator, H, of the frigorific machine keeps up the second rectification, which was brought about below the surrounding temperature, and which for this reason takes place without necessitating any combustion of coal. It suffices to cause the current of water which issues from the condenser of the frigorific machine to pass into the worm of the boiler.

We have, then, two results, two like operations, both produced by the working of a single machine. Moreover, these two operations are performed in vacuo, and we know that under these conditions they are effected at lower temperatures. Owing to this fact, likewise, the weight of the water that must be evaporated diminishes just so much. Now, one kilogramme of water requires 636 heat units to cause it to pass from the liquid to the gaseous state, while one kilogramme of alcohol requires only 230 heat units to vaporize it. Thus every decrease of temperature in rectification has for an immediate corollary an important economy of fuel, which is proved by the diminution of radiation, and by the less quantity of water to be distilled.

Between the boilers, A, in which is maintained a temperature bordering on +50 deg. to +60 deg., and the refrigerator, H, in which is easily obtained a temperature of -30 deg. to -40 deg., there is at our disposal a range of temperature of nearly 100 deg., an immense difference compared with that which can be made use of in ordinary apparatus. Thanks to this powerful factor, which is manageable at will, we can take directly from the apparatus alcohols marking 98 and 99 degrees by the centigrade alcoholmeter. Such results are unobtainable by the usual methods.

We have likewise ascertained that at low temperatures the ebullition of alcohol is as active as at near 100 deg..

For a same range of temperature between the boiler and the refrigerator, the weight of alcohol which distills in an hour is constant. By the operation of the valve, D, it becomes easy to allow all the liquid condensed in the first refrigerator to pass into the second boiler; and thus the second rectification, which is effected in a more perfect vacuum, is supplied with exactness. The object of this valve, then, is to allow the liquid to pass, and yet to cut off the pressure in such a way as to have a double fall of temperature throughout the whole apparatus; from 60 deg. to 20 deg. in the first operation, and from 0 deg. to -40 deg. in the second. We may add that the regulation of the valve is extremely easy, because of the screw which actuates it.

To sum up the commercial advantages that our process procures, we may say that it realizes the following desiderata: 1. With the cost of a single distillation we have, at once, distillation and rectification, or a single expense for two results. 2. With one operation at a low temperature we obtain products which are almost impossible to get even by an indefinite number of rectifications at a high temperature, the temperature having an intrinsic value in the operation. 3. The alcohols obtained are wholesome, and can be put on the market without danger. 4. Their superior quality gives these alcohols an extra value difficult to calculate, but which is very notable. 5. The whole operation being performed in closed vessels, there is absolutely no waste. 6. For the same reason there is scarcely any danger of fire. 7. The management of the works and the service are performed by the pressure of the gases entirely; there are only a few cocks to be turned to perform all the interior maneuvers, empty and fill the vessels, etc. Hence economy in personnel.

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ELECTROLYTIC DETERMINATIONS AND SEPARATIONS.

[Footnote: NOTE.—Each of these determinations was accompanied by a series of results in which the practical determinations obtained from the method described were compared with the theoretical contents of the solutions of the various elements. These, however, would take up too much room for insertion in these columns.]

By ALEX. CLASSEN and M.A. VON REIS; translated by M. BENJAMIN, Ph.B., F.C.S.

Ever since the electrolytic method for the estimation of copper came into general use, numerous chemists have endeavored to adapt this peculiarly simple and elegant method to the determination of other metals. According to the experiments which have been made up to the present time, it has been found that the separation of copper is best effected in a nitric acid solution, while that of nickel and cobalt takes place most readily in an ammoniacal solution, and for the precipitation of zinc and cadmium a potassium cyanide solution is the best. The accuracy of the results depend chiefly upon the following of certain fixed rules, such as, for instance, that the precipitation of copper only takes place when there is a definite amount of nitric acid in the solution; that of cobalt and nickel when a certain quantity of ammonium hydrate and ammonium sulphate is present. The electrolytic decomposition of the chlorides has not yet been successfully accomplished, so that prior to the operation it is necessary to convert them into sulphates. The experiments which have been made for the purpose of investigating the application of the electric current in quantitative analyses are very few, about the only exception being the separation of copper from the metals which are not precipitated from a nitric acid solution, or which are deposited as peroxides at the other electrode. We shall endeavor to show in that which follows, that copper, zinc, nickel, and cobalt, and even iron, manganese, cadmium, bismuth, and tin, whether they be present as sulphates, chlorides, or nitrates, may be precipitated and separated from each other by electrolytic methods much more rapidly than by any previously known process.

DETERMINATION OF COBALT.

Neutral potassium oxalate is added in excess to the solution of a cobalt salt, and the clear solution of cobalt potassium oxalate submitted to electrolysis. The intense red color of this solution is soon changed into a dark green; the latter diminishing in intensity as the metal is deposited at the negative electrode. The electric current decomposes the potassium oxalate into the carbonate, so that a precipitate of cobalt carbonate is simultaneously formed with the separation of the metallic cobalt. This precipitate may be dissolved by adding oxalic acid or dilute sulphuric acid; the further action of the current will change the solution to an alkaline reaction, upon which the treatment with acid is repeated until all the cobalt has been separated out in its metallic condition. The electrolytic separation of cobalt is much more easily and rapidly effected when the potassium oxalate is substituted by the corresponding ammonium salt, as the latter forms a soluble double salt with the cobalt compounds. If the ammonium oxalate added is just sufficient to form the double salt, a red cobalt oxalate (which is only slowly reduced by the current) will separate out in addition to the cobalt. In order to obviate this difficulty, the solution to which the ammonium oxalate had been added in excess is heated, and then three or four grammes more of solid ammonium oxalate are added. The hot solution, when exposed to the action of the current, deposits the cobalt as a closely adhering gray film. By the aid of two Bunsen's elements, 0.2 gramme cobalt can be separated in an hour's time. When the reduction has been completed, and this is best determined by testing a small sample (removed by a pipette) with ammonium sulphide, the positive electrode[1] is removed from the solution, and the liquid poured off. The dish is immediately rinsed several times with water, and the excess of water removed at first with alcohol, and then with absolute ether. The cobalt in the dish is dried in the air bath at 100 deg. C., and in the course of a few minutes a constant weight is obtained.

[Footnote 1: A piece of platinum foil, 4.5 cm. in diameter, is used for the positive electrode, and a deep platinum dish as the negative electrode.—Vide "Classen's Quantitative Analysis," 3d Edition, p. 46.]

DETERMINATION OF NICKEL.

This process is precisely identical with the previously described method for cobalt. The ammonium oxalate is added in excess to the solution, which is then heated, and four more grammes of the solid salt added. The separation of the nickel is as rapid as that of the cobalt. The nickel is precipitated as a gray, compact mass, tightly adhering to the electrode.

DETERMINATION OF IRON.

For this estimation, solutions of the chloride as well as those of the sulphate (ammonium, iron, alum) may be used in the manner previously described. The electrolysis is best effected in the presence of a sufficient quantity of ammonium oxalate; no separation of any iron compound takes place. The iron is deposited in the form of a bright, steel gray, firmly-adhering mass on the platinum dish. The iron may be exposed to the air for several days without any noticeable oxidation taking place.

DETERMINATION OF ZINC.

Zinc may be separated from a solution of the double salt fully as easily and rapidly as the previously mentioned metals were. The reduced zinc has a dark gray color, and adheres very firmly to the electrode. The separated metal is dissolved by using dilute acids and heating. It is only removed with difficulty, and generally leaves a dark coating on the dish, which is separated by repeated ignitions and treatment with acid.

DETERMINATION OF MANGANESE.

It is already known that manganese may be separated as the peroxide from its nitric acid solution. We find, however, that the precipitation is only completely effected when the quantity present is small; the amount of nitric acid must also be slight, and it is necessary to wash the dish without interrupting the current. If the manganese is converted into the soluble double salt, prepared by adding an excess of potassium, and submitted to the electric current, the whole of the manganese will be deposited at the positive electrode. When ammonium oxalate is used, the complete precipitation does not take place. As the separated peroxide does not adhere firmly to the electrode, it is necessary to filter it and convert it, by ignition, into the trimangano-tetroxide (Mn3O4).

DETERMINATION OF BISMUTH.

This separation presents considerable difficulty, because the metal is not precipitated as a compact mass on the platinum. The bismuth is always obtained in the same form, no matter whether it is precipitated from an acid solution, or from the double ammonium oxalate, or, finally, from a solution to which potassium tartrate has been added. As large a surface as possible must be used, and the dish piled to the rim; then, if the quantity of bismuth is small, the washing with water, alcohol, and ether may be effected without any loss of the element. If small quantities of the metal separate from the dish, they must be collected on a tared filter, and determined separately. In our experiments, an excess of ammonium oxalate was added to a nitric acid solution of bismuth. During the electrolytic decomposition, a separation of the peroxide was observed at the positive electrode, which, however, slowly disappeared. In order to prevent the reduced metal from oxidation, the last traces of water are completely removed by repeated washings with alcohol and anhydrous ether.

DETERMINATION OF LEAD.

The nitric solution of lead acts similarly to that of manganese. When the amount of peroxide separated is so large that it does not adhere firmly, and becomes mechanically precipitated on the negative electrode, it becomes impossible to complete the estimation without loss from the solution of the peroxide, and the results cannot be accepted.

If the double oxalate is submitted to electrolysis, the whole of the lead is separated out in its metallic state, but it is so rapidly oxidized by the air that it is very seldom that it can be dried without decomposition even when the operation is conducted in a current of illuminating gas. The electrolytic estimation of this element cannot be recommended.

DETERMINATION OF COPPER.

The copper may be very easily and rapidly separated from the double ammonium oxalate salt, provided a sufficient excess of ammonium oxalate is present. Weak currents cannot be employed for the determination of this element when it is present in large quantities, for under such circumstances the metal does not adhere with sufficient firmness to the electrode. We employed a current which corresponded to an evolution of 330 c.c. of gas per hour, and we were able to precipitate 0.15 gramme metallic copper in about twenty-five minutes.

DETERMINATION OF CADMIUM.

When the cadmium ammonium oxalate is submitted to the action of the electric current, the metal is thrown down in the form of a gray coating, which does not adhere very firmly to the electrode, but, however, sufficiently so as not to become separated on careful washing.

DETERMINATION OF TIN.

Tin may be easily estimated by electrolysis; it can be separated from its hydrochloric acid solution, or from its double salt with ammonium oxalate, as a beautiful silver gray coating on the platinum. When the ammonium oxalate is substituted by the potassium salt, the operation becomes more difficult, as a basic salt is formed at the opposite pole, and is not easily reduced. If the tin is separated from an acid solution, the current must not be interrupted while the washing takes place, a precaution which it is not necessary to follow when the ammonium oxalate is used. When the tin is dissolved from the platinum dish, it acts like the zinc; that is to say, a black coating is left on the electrode.

DETERMINATION OF ANTIMONY.

Antimony may be precipitated in its metallic state from a hydrochloric acid solution, but it does not adhere very firmly to the electrode. If potassium oxalate is added to a solution of the trichloride, the antimony may be readily reduced, but the metal adheres still less firmly to the electrode than it did in the first instance. An adherent coating may be obtained by adding an alkaline tartrate, but in that case the separation takes place too slowly. The precipitation of antimony may be very readily effected from solutions of its sulpho salts.

To a liquid, which may contain free hydrochloric acid, hydrogen sulphide is added, then neutralized with ammonium hydrate, and saturated with ammonium sulphide in excess. The reduction may be accelerated by the addition of some ammonium sulphate. The antimony separates out as a fine, light gray precipitate on the electrode, and which adheres very firmly, provided the precipitation has not been carried on too rapidly, i. e., if the current employed for the reduction was not too strong.

When the reduction has been completed, the supernatant liquid is poured off, and the residue washed in the ordinary manner.

DETERMINATION OF ARSENIC.

Arsenic cannot be completely separated from either its aqueous hydrochloric acid, or from a solution to which ammonium oxalate has been added in excess. From its aqueous as well as from its oxalate solution, a portion of the metal may be separated, but if the current is passed through its hydrochloric acid solution for a sufficient length of time, all the arsenic will be volatilized as arsenious hydride (AsH_3).

SEPARATION OF IRON FROM MANGANESE.

If a solution of ferric oxide and manganese ammonium oxalate is submitted to electrolysis, without the previous addition of ammonium oxalate, the characteristic color of permanganic acid immediately makes its appearance, and the peroxide gradually precipitates itself on the positive, while the iron is deposited on the negative electrode. When the examination is made in the above manner, it is impossible to separate the two metals, for the peroxide will bring down with it a considerable quantity of ferric hydrate. The separation of the two metals is only possible when the precipitation of the manganese peroxide is prevented, until the greater portion of the iron has been deposited. This result may be attained by adding sodium phosphate, or, better still, by the addition of ammonium oxalate in great excess. In both cases the characteristic coloration from permanganic acid is developed by the action of the current at the positive pole; this, however, disappears in the direction of the negative electrode. After the greater portion of the ammonium oxalate has been converted into carbonate, the coloration and necessarily the formation of manganese peroxide begins.

Ammonium oxalate is added to the solution, and heat applied; then three or four grammes more of ammonium oxalate are dissolved in the liquid, which is then immediately submitted to electrolysis. When the amount of manganese is small, the separation of the two elements takes place very rapidly, and the results are accurate. If the amount of manganese is more than double that of iron, the separation of the latter will take a much longer time. Then, in order to effect a complete separation of the two elements, it is necessary to redissolve the deposited manganese in oxalic acid (the acid is added, without interrupting the current, until the liquid becomes red), and the current is allowed to continue its action.

It was found desirable, in effecting this separation, not to employ too strong a current (two Bunsen elements will suffice), and only to increase the strength of the current when it is necessary, in consequence of a large amount of manganese being present, to redissolve the peroxide.

When the process is completed, it is not advisable to allow the current to act any longer, for otherwise some of the peroxide may adhere firmly to the iron, and the latter (after previously having poured off the liquid) must be redissolved in oxalic acid, that is to say, the electrolysis must be repeated. As has been already mentioned in the determination of manganese as peroxide, its precipitation from ammonium oxalate is not complete. The solution which contains the greater portion of manganese, suspended as peroxide, must first, therefore, be boiled to decompose the ammonium carbonate; the remainder of the ammonium oxalate is neutralized with nitric acid, and the manganese converted into the sulphide by ammonium sulphide. The manganese sulphide is then ignited in a current of hydrogen, and weighed as such.

SEPARATION OF IRON AND ALUMINUM.

The quantitative separation of iron from aluminum, which presented many difficulties according to the older methods, may be easily performed by electrolysis. If a solution of iron ammonium oxalate and aluminum oxalate, to which an excess of ammonium oxalate has been added, be submitted to the action of the electric current, the iron will be deposited as a firmly adhering coat on the negative electrode, while the aluminum oxide remains in solution, just so long as the quantity of ammonium oxalate is in excess of the quantity of ammonium carbonate produced. When, finally, a precipitation of aluminum oxide takes place the liquid is almost free from iron. From time to time, the solution, in which the aluminum oxide is suspended, is tested for iron by ammonium sulphide, and the current is interrupted when no further reaction is observed. The best method of procedure is to add ammonium oxalate in excess to a neutral, a slightly acid solution, or to one which has been neutralized by the addition of ammonium hydrate (a hydrochloric acid solution is not well adapted for this purpose); then as much more solid ammonium oxalate is added until for every 0.1 gramme there is 2 to 3 grammes of the oxalate present. The hot solution is then directly submitted to the action of the electric current. After the iron has been precipitated, it is best to stop the action of the current before all the aluminum oxide is thrown down, for otherwise a portion of the latter may adhere firmly to the iron, and be difficult to remove.

In such a case, as was mentioned previously in the separation of iron from manganese, it is necessary to redissolve the iron (after previously having poured off the liquid) in oxalic acid, and then the electrolysis is continued.

In order to effect the complete precipitation of the aluminum oxide from the solution which was poured from the iron, ammonium hydrate is added, and the solution boiled for some time, and then the aluminum oxide is determined in the usual manner. When the quantity of aluminum is less than that of iron, this method may be relied upon to give exact results. With the reverse (i. e., an excess of iron) the precipitate of aluminum oxide must be dissolved in oxalic acid (without the interruption of the current), and the electrolysis continued.—Berichte der Deutschen Chemischen Gesellschaft, 14, 1662.

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THE CULTIVATION OF PYRETHRUM AND MANUFACTURE OF THE POWDER.

In accordance with an announcement in the March number of the Naturalist, the editor of this department has sent out the seed of two species of pyrethrum, viz. P. roseum and P. cinerarioefolium, to a large number of correspondents in different parts of North America. Every mail brings us some inquiries for further particulars and directions to guide in the cultivation of the plant and preparation of the powder. We have concluded, therefore, that such information as is obtainable on these heads will prove of public interest, and we shall ask Professor Bessey's pardon for trenching somewhat on his domain.

There are very few data at hand concerning the discovery of the insecticide properties of pyrethrum. The powder has been in use for many years in Asiatic countries south of the Caucasus mountains. It was sold at a high price by the inhabitants, who successfully kept its nature a secret until the beginning of this century, when an Armenian merchant, Mr. Jumtikoff, learned that the powder was obtained from the dried and pulverized flower-heads of certain species of pyrethrum growing abundantly in the mountain region of what is now known as the Russian province of Transcaucasia. The son of Mr. Jumtikoff began the manufacture of the article on a large scale in 1828, after which year the pyrethrum industry steadily grew, until to-day the export of the dried flower-heads represents an important item in the revenue of those countries.

Still less seems to be known of the discovery and history of the Dalmatian species of pyrethrum (P. cinerarioefolum), but it is probable that its history is very similar to that of the Asiatic species. At the present time the pyrethrum flowers are considered by far the most valuable product of the soil of Dalmatia.

There is also very little information published regarding either the mode of growth or the cultivation of pyrethrum plants in their native home. As to the Caucasian species we have reasons to believe that they are not cultivated, at least not at the present time, statements to the contrary notwithstanding.[1]

[Footnote 1: Report Comm. of Patents, 1857, Agriculture, p. 130.]

The well-known Dr. Gustav Radde, director of the Imperial Museum of Natural History at Tiflis, Transcaucasia, who is the highest living authority on everything pertaining to the natural history of that region, wrote us recently as follows: "The only species of its genus Pyrethrum roseum, which gives a good, effective insect powder, is nowhere cultivated, but grows wild in the basal-alpine zone of our mountains at an altitude of from 6,000 to 8,000 feet." From this it appears that this species, at least, is not cultivated in its native home, and Dr. Radde's statement is corroborated by a communication of Mr. S. M. Hutton, Vice-Consul General of the U. S. at Moscow, Russia, to whom we applied for seed of this species. He writes that his agents were not able to get more than about half a pound of the seed from any one person. From this statement it may be inferred that the seeds have to be gathered from the wild and not from the cultivated plants.

As to the Dalmatian plant it is also said to be cultivated in its native home, but we can get no definite information on this score, owing to the fact that the inhabitants are very unwilling to give any information regarding a plant the product of which they wish to monopolize. For similar reasons we have found great difficulty in obtaining even small quantities of the seed of P. cinerarioefolium that was not baked or in other ways tampered with to prevent germination. Indeed, the people are so jealous of their plant that to send the seed out of the country becomes a serious matter, in which life is risked. The seed of Pyrethrum roseum is obtained with less difficulty, at least in small quantities, and it has even become an article of commerce, several nurserymen here, as well as in Europe, advertising it in their catalogues. The species has been successfully grown as a garden plant for its pale rose or bright pink flower-rays. Mr. Thomas Meehan, of Germantown, Pa., writes us: "I have had a plant of Pyrethrum roseum in my herbaceous garden for many years past, and it holds its own without any care much better than many other things. I should say from this experience that it was a plant which will very easily accommodate itself to culture anywhere in the United States." Peter Henderson, of New York, another well-known and experienced nurseryman, writes: "I have grown the plant and its varieties for ten years. It is of the easiest cultivation, either by seeds or divisions. It now ramifies into a great variety of all shades, from white to deep crimson, double and single, perfectly hardy here, and I think likely to be nearly everywhere on this continent." Dr. James C. Neal, of Archer, Fla., has also successfully grown P. roseum and many varieties thereof, and other correspondents report similar favorable experience. None of them have found a special mode of cultivation necessary. In 1856 Mr. C. Willemot made a serious attempt to introduce and cultivate the plant[1] on a large scale in France. As his account of the cultivation of pyrethrum is the best we know of we quote here his experience in full, with but few slight omissions: "The soil best adapted to its culture should be composed of pure ground, somewhat silicious and dry. Moisture and the presence of clay are injurious, the plant being extremely sensitive to an excess of water, and would in such case immediately perish. A southern exposure is the most favorable. The best time for putting the seeds in the ground is from March to April. It can be done even in the month of February if the weather will permit it. After the soil has been prepared and the seeds are sown they are covered by a stratum of ground mixed with some vegetable mould, when the roller is slightly applied to it. Every five or six days the watering is to be renewed, in order to facilitate the germination. At the end of about thirty or forty days the young plants make their appearance, and as soon as they have gained strength enough they are transplanted at a distance of about six inches from each other. Three months after this operation they are transplanted again at a distance of from fourteen to twenty inches, according to their strength. Each transplantation requires, of course, a new watering, which, however, should only be moderately applied. The blossoming of the pyrethrum commences the second year, toward the end of May, and continues to the end of September." Mr. Willemot also states that the plant is very little sensitive to cold, and needs no shelter, even during severe winters.

[Footnote 1: Mr. Willemot calls his plant Pyrethre du Caucase (P. Willemoti. Duchartre), but it is more than probable that this is only a synonym of P. roseum. We have drawn liberally from Mr. Willemot's paper on the subject, a translation of which may be found in the Report of the Commissioner of Patents for the year 1861, Agriculture, pp. 223-331.]

The above quoted directions have reference to the climate of France, and as the cultivation of the plant in many parts of North America is yet an experiment, a great deal of independent judgment must be used. The plants should be treated in the same manner as the ordinary Asters of the garden or other perennial Compositae.

As to the Dalmatian plant, it is well known that Mr. G. N. Milco, a native of Dalmatia, has of late years successfully cultivated Pyrethrum cinerarioefolium near Stockton, Cal., and the powder from the California grown plants, to which Mr. Milco has given the name of "Buhach," retains all the insecticide qualities and is far superior to most of the imported powder, as we know from experience. Mr. Milco gives the following advice about planting—advice which applies more particularly to the Pacific coast: "Prepare a small bed of fine, loose, sandy, loamy soil, slightly mixed with fine manure. Mix the seed with dry sand and sow carefully on top of the bed. Then with a common rake disturb the surface of the ground half an inch in depth. Sprinkle the bed every evening until sprouted; too much water will cause injury. After it is well sprouted, watering twice a week is sufficient. When about a month old, weed carefully. They should be transplanted to loamy soil during the rainy season of winter or spring."

Our own experience with P. roseum as well as P. cinerarioefolium in Washington, D. C., has been so far quite satisfactory. Some that we planted last year in the fall came up quite well in the spring and will perhaps bloom the present year. The plants from sound seed which we planted this spring are also doing finely, and as the soil is a rather stiff clay and the rains have been many and heavy, we conclude that Mr. Willemot has overstated the delicacy of the plants.

In regard to manufacturing the powder, the flower heads should be gathered during fine weather when they are about to open, or at the time when fertilization takes place, as the essential oil that gives the insecticide qualities reaches, at this time, its greatest development. When the blossoming has ceased the stalks may be cut within about four inches from the ground and utilized, being ground and mixed with the flowers in the proportion of one-third of their weight. Great care must be taken not to expose the flowers to moisture, or the rays of the sun, or still less to artificial heat. They should be dried under cover and hermetically closed up in sacks or other vessels to prevent untimely pulverization. The finer the flower-heads are pulverized the more effectually the powder acts and the more economical in its use. Proper pulverization in large quantities is best done by those who make a business of it and have special mill facilities. Lehn & Fink, of New York, have furnished us with the most satisfactory powder. For his own use the farmer can pulverize smaller quantities by the simple method of pounding the flowers in a mortar. It is necessary that the mortar be closed, and a piece of leather through which the pestle moves, such as is generally used in pulverizing pharmaceutic substances in a laboratory, will answer. The quantity to be pulverized should not exceed one pound at a time, thus avoiding too high a degree of heat, which would be injurious to the quality of the powder. The pulverization being deemed sufficient, the substance is sifted through a silk sieve, and then the remainder, with a new addition of flowers, is put in the mortar and pulverized again.

The best vessels for keeping the powder are fruit jars with patent covers or any other perfectly tight glass vessel or tin box.—American Naturalist.

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THE REMOVAL OF NOXIOUS VAPORS FROM ROASTING FURNACE GASES.

In a paper read before the Aix-la-Chapelle section of the Verein deutscher Ingenieure, Herr Robert Hasenclever presents a summary of the results obtained with various methods for the absorption of the sulphurous acid generated during the roasting of zinc-blende and other sulphurets. Though most of our own metallurgical works are not so located as to be forced to pay much attention to the removal of noxious vapors, the efforts made abroad possess some interest for American metallurgists. Besides containing sulphurous acid, the gases from the roasting furnaces hold varying quantities of sulphuric acid, and Dr. Bernoulli describes a process applied on a large scale in Silesian zinc works, where the gases were passed through towers filled with lime. It was found that there was no trouble on account of the absorption of carbonic acid by the lime, and that the latter acted very efficiently in reducing the quantity of sulphurous acid. Before entering the tower, they contained 0.258 per cent. by volume of sulphurous acid and 2.45 per cent. of carbonic acid; while, after their passage through it, they held 0.017 and 2.478 per cent, respectively. The process, however, is declared by Herr Hasenclever to be too costly for ordinary working, although he does not deny its value under special circumstances.

The removal of anhydrous sulphuric acid from the gases from roasting-furnaces has hitherto, as at the Waldmeister works, near Stolberg, been effected by means of water trickling down in a tower filled with coke, the gases entering below and moving upward. Herr Hasenclever tested the Freytag method, in which the water is replaced by sulphuric acid, and obtained favorable results, as shown by the following analyses of the gases before and after treatment. The figures given are grammes per 1,000 liters:

BEFORE. AFTER. SO2. SO3. SO2. SO3. 8.24 0.63 5.74 0.00 8.29 0.37 6.74 0.07 9.36 0.69 6.96 0.00 9.46 0.63 7.38 0.05 10.03 1.08 7.69 0.09 16.52 2.97 14.39 0.23 17.90 1.97 13.32 0.11 17.80 2.46 16.18 0.69

The average absorption for the first set of four analyses when three roasting-furnaces were discharging into the tower was 95 per cent. of the sulphuric acid, and that of the second set of four or five furnaces was 90 per cent. The amount of sulphuric acid charged per twenty-four hours was about 5,000 kilogrammes of 50 degrees Baume, which flowed off with a density of from 56 to 58 degrees Baume. The quantity of acid condensed varied according to the nature of the ores and the number of furnaces working. It ranged between 300 and 1,000 kilogrammes of 60 degrees Baume per twenty-four hours. The condensation of anhydrous sulphuric acid would pay, according to estimates submitted by Herr Hasenclever; but to pass the gases through a tower filled with lime, in order to get rid of the remaining sulphurous acid, would prove too expensive at Stolberg. An attempt to use milk of lime proved partially successful; but it was not followed up, because it was decided to experiment with the process suggested by Prof. Cl. Winkler, of Freiberg, who proposes to pass the gases through a tower filled with iron in some suitable shape, over which water trickles. From the solution thus obtained, sulphurous acid pure enough to be used for the manufacture of sulphuric acid, sulphur, and a solution of green vitriol is made. Experiments with this process are making at Freiberg and at the Rhenania Works, near Stolberg. The trouble with the majority of methods thus far is, that the draught of the furnaces is so much impeded by the absorption towers that fans, blowers, or steam jets must be used to carry the gases through it.

The experience of Herr Hasenclever has proved how difficult it is to find a satisfactory means of removing the noxious vapors from furnace gases without incurring too serious an expense. Thus far the value of the products obtained by absorption of sulphurous acid has not been equal to the cost of producing them. Herr C. Landsberg, who is general manager of the Stolberg Company, has had similar experience, though his experiments were made to test methods suggested at various times by Dr. E. Jacob and Dr. Aarland. Both are very ingenious, and were successful on a small scale, but failed when tried in actual working.—Engineering and Mining Journal.

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NEW GAS EXHAUSTER.

In common practice, the new exhauster at the Old Kent Road passes about five million cubic feet of gas per day of twenty-four hours, and requires the attention of two men and two boys for driving and stoking, at the following cost:

s. d. Wages—2 men, at 5s. 6d 11 0 Wages—2 boys, at 3s. 6d 7 0 ——- L 0 18 0 Oil, 1 gallon 0 3 6 Waste, 5 lb 0 1 0 ———— Total L 1 2 6

for five million cubic feet, or 0.054d. per 1,000 feet. The boiler burns a mixture of coke and breeze, chiefly the latter, of small value, costing 0.0174d. per 1,000 feet of gas exhausted; therefore the total cost of exhausting gas by the new system is—

Fuel 0.0174d Wages, oil, and waste 0.0540 ———— Total 0.07l4d.

per 1,000 cubic feet of gas, exclusive of repairs, which will be decidedly less for the new exhauster than for that on the older system, from the friction being so much less. The feed water evaporated is at the rate of about 7.4 lb. per pound of breeze, and 7.5 lb. per pound of coke.



It will be seen that the exhausting arrangements at the Old Kent Road are extremely economical, the cost of fuel being reduced to a minimum; while a man and boy by day, and their reliefs for the night, attend to the machinery inside the exhauster-house, and also to the pumps outside, and stoke the boiler as well.—Journal of Gas Lighting.

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ADVANCE IN THE PRICE OF GLYCERINE

The continued advance in the price of glycerine continues to excite comment among those who deal in or use it, and no one seems to know exactly where or when the advance is likely to stop, or by what means a retrograde movement will probably be brought about.

As we have heretofore stated, the rise has been brought about by a combination of two causes—a falling off in production and a great increase in the demand, owing to the discovery of new uses for it, and the extension of the branches of manufactures in which it has been heretofore employed.

In pharmacy, it is coming more and more into use daily, and in various other branches of manufacture the same tendency is observable. It has proved itself so elegant and so convenient a vehicle for the administration of various medicinal substances, is so easily miscible with both water and alcohol, and is so pleasant to the taste, that it seems almost a wonder that it should have been so long in attaining the rank among the articles of the Materia Medica which it now occupies. The two manufactures, however, which seem to lead in the demand for glycerine are of nitro-glycerine and of oleomargarine.

The uses to which it is put for the former are well known, but precisely what the latter could want of the article is not, at first glance, quite so obvious. We are informed, however, that it is valued for its antiseptic properties, and also for its softening effect on the quasi butter. Be this as it may, it seems that both here and in Europe the makers of these two articles are buying largely of both crude and refined glycerine.

So it appears that the willingness of the people to eat artificial butter, and the progress in schemes for internal improvement, such as the De Lesseps Canal, for instance, to say nothing of the European revolutionists, are responsible to a great extent for the scarcity of an important article of pharmaceutical use.

On the other hand, while there is a notable increase in the demand for the article, there is a gradual but very sure and noticeable falling off in the production.

At present the supply for the whole world comes from the candlemakers of Europe—chiefly France and Germany—and, as improved methods of illumination push candles out of the drawing rooms of the wealthier as well as the cabins of the poor, and consequently out of the markets, the production of glycerine naturally grows less. In France, for instance, candles are coming to be regarded among the wealthy chiefly as articles of luxury, and are lighted only for display at festivals of especial magnificence and ceremony, while among the poor the kerosene lamp is coming into almost as universal use as here.

To be sure, the inexorable inn-keeper still keeps up, we believe, the inevitable bougie, but even that is fast becoming more of a fiction than ever. Even in the churches, it is said, the use of candles is gradually falling off. To these causes must be attributed the decreasing supply of the crude material, but it may be doubted whether this decrease would be sufficient to materially affect the price for some time to come were it not for the increased demand for the two industries to which we have alluded. Obviously, there must be found eventually some substitute for glycerine, or else some new source from which it may be procured. The natural place to look for this would be in the waste lye from the soapmakers' boilers, but so far no one has succeeded in obtaining from this substance the glycerine it undoubtedly contains by any process sufficiently cheap to allow of its profitable employment.

We are assured by a veteran soap-boiler who has experimented much in this direction that it is impossible to recover a marketable article of glycerine from the lees of soap in which resin is an ingredient. In his words, it "kills the glycerine," and, as none but a few of the finest soaps are now made without resin, it would seem that the search for glycerine in this direction must be a hopeless one. It is a curious commentary in the present state of affairs that previous to about 1857, when candles were largely manufactured in this country, there was little or no demand for glycerine, and millions of pounds of it were run into the sewers. Even then, however, the use of it as a wholesome and pleasant article of diet was known to the workmen employed in the candle factories, who were accustomed to drink freely of the mingled glycerine and water which constituted the waste from the candles. Yet with this fact under their noses, as it were, it is only recently that members of the medical profession have begun to recommend the same use of glycerine as a substitute for cod liver oil.—Pharmacist.

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ANALYSIS OF OILS, OR MIXTURES OF OILS, USED FOR LUBRICATING PURPOSES.

Oils, fats, waxes, and bodies somewhat similar in nature, may—according to the substance of a paper recently read before the Chemical Society, by Mr. A. H. Allen, of Sheffield, and Mr. Thomson, of Manchester—be divided into two great classes, viz., those which combine with soda, potash, or other alkalies to form soaps, and those which do not; and as those two classes of bodies differ materially in their actions on substances such as iron, copper, etc., with which they come in contact, it often becomes a question of great importance to the users of oils for lubricating purposes to know what proportions of these different substances are contained in any oil or mixture of oils. The object of the authors was to give accurate methods for determining the percentages of these bodies contained in any sample. Hydrocarbon or mineral oils are now much used for lubricating the cylinders of engines, and especially of condensing engines, and that for two reasons—first, because they are neutral bodies, which have no action on metals; and, second, that they are not liable to deposit on the boilers, if they should happen to be introduced with the condensed water so as to produce burning of the ironwork over the flues.

Animal or vegetable oils or fats are composed of fatty acids in combination with glycerine, and these, under the influence of high-pressure steam, are decomposed or dissociated, the fatty acids being liberated from the glycerine, leaving the former to act upon or corrode the iron of the cylinder. But here their objectionable influence does not end. They form with the iron hard, insoluble compounds called iron soaps, which increase the friction between the cylinder and piston, and in some cases gradually collect into the form of hard balls inside the cylinder.

When the water is used over and over again a considerable proportion of the fatty acids of the oils used for lubricating the piston is carried over with the steam and is found in the condensed water which is introduced into the boiler along with the water. Here it commences action, which proves quite as injurious to the boiler as it does to the cylinder, but in a different way. It acts upon the iron of the boiler and on some of the lime salts which constitute the incrustation, forming greasy iron and lime soaps, which prevent the water from coming into absolute contact with it. Thus the heat cannot be drawn away quickly enough by the water, and the plates thus coated above the flues are liable to become burdened and weakened. This action has in many cases gone on to such an extent that the flues have collapsed under the pressure of the steam inside.

The authors give two different processes for the determination of animal or vegetable oils or fats and hydrocarbon or other neutral oils. They take a certain weight of the sample and boil it with twice its weight of an eight per cent, solution of caustic soda in alcohol. The soda combines with the fatty acids of the animal or vegetable oils forming soaps; bicarbonate of soda is then added to neutralize the excess of caustic soda; and, lastly, sand; and the whole is evaporated to dryness at the temperature of boiling water. The dry mixture is then transferred to a large glass tube, having a small hole in the bottom plugged with glass wool to act as a filter, and light petroleum spirit—which boils at about 150 deg. to 180 deg. Fahr.—is poured over it, till all the neutral or unsaponifiable oil is dissolved out. In the other process no sand is used, but the dry mixture is dissolved in water, and the soap solution which holds the neutral oils in solution is treated with ether, which dissolves out the neutral oil and then floats to the surface of the liquid. The ether solution is then drawn off, and the ether in the one case and petroleum spirit in the other are separated from the dissolved oils by distillation, the last traces of these volatile liquids being separated by blowing a current of filtered air through the flask containing the neutral oil, which is then weighed and its percentage on the original sample calculated.

All animal and vegetable oils yield a small quantity—about one per cent.—of unsaponifiable fatty matter, which must be deducted from the result obtained. Sperm oil, however, was found to be an exception, because from its peculiar chemical constitution it yields nearly half its weight of a greasy substance to the ether or to the petroleum spirit. The substance, however, dissolved from sperm oil after saponification has the appearance of jelly, when the ether or petroleum spirit solution is concentrated and allowed to cool, and the presence of sperm oil can thus be readily detected. Solid paraffin, heavy petroleum or paraffin oils, and rosin oil—which is produced by the destructive distillation of rosin—are not saponifiable, and yield about the whole of the amount employed to the petroleum spirit or ether. Japan wax is almost entirely saponifiable, while beeswax and spermaceti yield about half their weights to the petroleum spirit or ether.

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NITRITE OF AMYL.

Dr. Edgar Kurtz, of Florence, has found this medicament so useful in the various aches and pains of every-day life that he has persuaded many families of his acquaintance to keep it on hand as a domestic remedy. It is an excellent external application for stomach-ache, colic, tooth ache (whether nervous or arising from caries), neuralgia of the trigeminus, of the cervico-brachial plexus, etc. It is superior to anything else when inhaled in so-called angio-spastic hemicrania, giving rapid relief in the individual paroxysms and prolonging the intervals between the latter. No trial was made in cases of angio paralytic hemicrania, since in this affection the drug would be physiologically contraindicated. It has a very good effect in dysmenorrhoea, especially when occurring in chlorotic girls; in mild cases external applications suffice, otherwise the drug should be inhaled (when complicated with inflammatory conditions of the uterus or appendages the results were doubtful or negative). Its physiological action being that of a paralyzing agent of the muscular tissue of the blood vessels, with consequent dilatation of their caliber (most marked in the upper half of the body), nitrite of amyl is theoretically indicated in all conditions of cerebral anaemia. Practically it was found to be of much value in attacks of dizziness and faintness occurring in anaemic individuals, as also in a fainting-fit from renal colic, and in several cases of collapse during anaesthesia by chloroform.

It has been recommended in asphyxia from drowning, hanging, and in asphyxia of the new born, but the first indication in these cases is the induction of artificial respiration, after the successful initiation of which inhalations of nitrite of amyl doubtless assist in overcoming the concomitant spasm of the smaller arteries.

One of the most important indications for the use of the drug is threatening paralysis of the heart from insufficient compensation. In such cases it is necessary to gain time until digitalis and alcoholics can unfold their action, and here nitrite of amyl stands pre-eminent. A single case in point will suffice to illustrate this. The patient was suffering from mitral insufficiency, with irregular pulse, loss of appetite, enlargement of the liver, and mild jaundice. Temporary relief had been several times afforded by infusion of digitalis. In February, 1879, the condition of the patient suddenly became aggravated. The pulse became very irregular and intermittent. The condition described as delirium cordis presented itself, together with epigastric pulsation and vomiting. Vigorous counter-irritation, by means of hot bottles and sinapisms to the extremities, etc., proved useless. Digitalis and champagne, when administered, were immediately vomited. The pulse ran up from seventy until it could no longer be counted at the wrist, while the beats of the heart increased to one hundred and twenty and more per minute. The extremities grew cold, and the face became covered with perspiration. The urine was highly albuminous. Nitrite of amyl was then administered by inhalation: at first, three to five drops; then, ten to twenty; and finally, more or less was poured on the handkerchief without being measured. During each inhalation the condition of the patient rapidly improved, but as quickly grew worse, so that the drug was continued at short intervals all night, ten grammes in all having been used. In the morning the patient was better, and 0.5 gramme of digitalis was then given in infusion per rectum, and repeated on the following day, after which the patient remained comparatively well until a year and a half later, when a second attack of the kind just described was quickly cut short by similar treatment.